1. Field of the Invention
This invention relates to a guidance device for a flexible curtain containing horizontal cross-pieces forming the panel of a motor-driven flexible curtain door, allowing the panel to be moved quickly between a closed position and an open position.
The guidance device in this invention is intended in particular for doors in which the flexible curtain is either rolled around a drum or folded, concertina-style, in a given space.
2. Description of Background and Relevant Information
There are known flexible curtain doors which have two vertical, parallel metal supports in a U or C shape which can be fitted either directly into a concrete frame on which the door is fitted, or via elastic components placed between the vertical jambs of the concrete frame and the metal supports, as described in European patent application No. 92 909384.
Each metal support receives a straight guidance path in which the lateral edges of the flexible curtain run when it is moved between a closed position and an open position.
The guidance paths are made from channel in which a slideway is placed to guide the lateral edges of the curtain in each direction. Each guidance path includes a slideway whose internal profile is roughly square, with one edge having a slot running the full height of the said guidance path for the curtain to pass along.
The guidance paths are made of a semi-elastic material, so that when a pulling force is exerted on the curtain, the lateral edges of the curtain are released from the guidance paths.
This type of flexible curtain door has certain problems in that it is impossible to have access to and to clean the internal walls of the slideways fitted in each guidance path. When these doors are installed in rooms where food products are processed, it is essential to clean the door, and in particular the guidance paths completely after each day's work. The structure of the guidance paths described above means that this procedure is impossible without completely dismantling the door.
In addition, the guidance paths have very low resistance to impact, since the semi-elastic material of which the section is made is weakened by the slot made along its full height.
Slideways are more traditionally made of an open, U-shaped section the width across which is identical from top to bottom, a solution which is unsuitable for the way in which these doors operate.
Thus for concertina-style flexible curtain doors, these slideways have made it necessary to accommodate, when the door is open, a significant volume of stacked slats, while the passage that is necessary and sufficient in the closed position is limited to the thickness of the door.
Similarly, for roll-up doors, the curtain shifts in its vertical plane because of the change in the diameter of the roller curtain, depending on whether it is in the open or closed position. It is therefore recommended that the upper part of the slideway should be wider, to allow the panel to drop without restriction and without friction.
The guidance device in this invention is intended to correct these problems.